Resistor ignition lead

ABSTRACT

The invention is directed to a non-metallic resistor ignition cable having a core including a conductive coating over strands of non-conductive material. The strands are impregnated with a conductive medium prior to or at the time of application of the conductive coating. Outer insulation is supplied which is stripped off to expose the coated strands. A terminal is applied to the stripped end of the cable by crimping a ferrule portion around the end of the outer insulation and the folded back coated strands.

United States Patent [131 Barker et a1.

RESISTOR IGNITION LEAD Inventors: Robert A. Barker; John W. Shank,

both of Port Huron, Mich.

Assignee: Eltra Corporation, Brooklyn, NY.

Filed: Nov. 7, 1966 Appl. No.: 595,305'

Related US. Application Data Division of Ser. No. 3l5,464, Oct. 11,1963, Pat. No. 3,284,75 1.

us. c1. 339/223 s, 339/26, 338/214 L'JLLL'LS L 7: IL L l. f' i9v..339/223,26, 115; 338/66,

References Cited UNITED STATES PATENTS 2/1934 Rowley 339/223 8/1948Peterson 338/214 X Jan. 22, 1974 2,451,800 10/1948 Buchanan et a1339/223 S 2,714,623 8/1955 W'zllCOtt 174/120.l

Primary ExaminerJoseph H. McGlynn Assistant Examiner-Robert A. HaferAttorney, Agent, or FirmD. Henry Stoltenberg; Vincent L. Barker, Jr.

[5 7 ABSTRACT The invention is directed to a non-metallic resistorignition cable having a core including a conductive coating over strandsof non-conductive material. The strands are impregnated with aconductive medium prior to or at the time of application of theconductive coating. Outer insulation is supplied which is stripped offto expose the coated strands. A terminal is applied to the stripped endof the cable by crimping a ferrule portion around the end of the outerinsulation and the folded back coated strands.

2 Claims, 8 Drawing Figures PAIENIEUJANwQM m R we K ERK VMN m m S TW R NWH Rm ATTORNEYS 1 RESISTORIGNITION LEAD This application is a divisionof our copending application Ser. No. 315,464, filed Oct. 11, 1963, nowUS. Pat. No. 3,284,751.

This invention relates to ignition cables, more particularly to anignition cable which incorporates a nonmetallic conductor havinguniformly distributed resistance per unit length of the cable which isprovided with a special means for making electrical contact between thenon-metallic conductor and metallic tenninals which are positioned oneach end of the ignition cable.

With the advent in the automotive industry of longterm service warrantyagreements wherein the automobile company accepts responsibility for theoperability of various parts of the automotive vehicle for a period oftime extending to 60 months or to a driving mileage extending to 50,000miles, it has become very essential that all of the elements of theautomotive vehicle and of the ignition system particularly, shall besufficiently durable to be servicable through this period of time orover this driving distance. In the past, car companies have found thatignition cables, which have distributed resistance for the suppressionof radioand television interfering emanations arising from highfrequency oscillations, having been particularly vulnerable to breakdownduring the warrenty period described hereinbefore so that it has beennecessary to replace complete sets of ignition cables to satisfy theconditions of the service warranty. This has been very burdensome andexpensive for the automobile vehicle manufacturers, particularly due tothe fact that itcould not be clearly established whether the breakdownin service within the warranty period arose from the inherent weaknessof the ignition cable or whether it arose from careless handling on thepart of servicemen attempting to repair the engine. I The presentinvention contemplates providing an ignition cable which has improvedphysical and electrical characteristics which will obviate the problemspointed out hereinbefore. The ignition cable incorporating the inventionhas the inherent durability to satisfy these service requirements underthe warranty during normal use of the automotive vehicle, and also hassufficient durability to remain efficient even though it has beensubjected to careless handling on the part of a repairman.

The invention further contemplates the provision of a new method ofmaking connection between a nonmetallic resistive conductor of anignition cable to the metallic terminal at the ends thereof by providinga reliable means of making electrical contact to the metallic terminalwhich has physical and electrical characteristics to remain effectiveduring the warranty period of the automotive vehicle.

It is therefore a principal object of this invention to provide anon-metallic resistive-type ignition cable to suppress radiointerference emanations which has the physical and electricalcharacteristics to be effective for engine operation for automotivevehicles under extended warranty periods.

It is a further object of this invention to provide a means ofconnecting a non-metallic resistive conductor of an ignition cable whichwill suppress radio and television interfering emanations due to highfrequency oscillations to metallic terminal members which will have thephysical and electrical characteristics to satisfy the servicerequirements of automotive vehicles arising under extended warrantyperiods, even though the cable is subjected to rough usage by repairmenworking on the automotive vehicle.

Other objects and advantages of this invention relating to thearrangement, operation and function of the related elements of thestructure, to various details of construction, to combinations of partsand to economies of manufacture will be apparent to those skilled in theart upon consideration of the following description and appended claims,reference being had to the accompanying drawings forming a part of thisspecification wherein like reference characters designate correspondingparts in the several views.

Referring to the drawings:

FIG. 1 is a perspective view with cut-away portions showing an ignitioncable having a resistive nonmetallic conductor.

FIG. 2 is an elevational view of a portion of the ignition cable cut tolength.

FIG. 3 is an elevational view of the cable portion shown in FIG. 2 withthe insulation cut-away at its terminal ends to prepare the non-metallicconductor for connecting to terminals.

FIG. 4 is an elevational view similar to FIG. 3 showing the non-metallicconductor bent back over the insu lation at both ends.

FIG. 5 is an elevational view of the ignition cable shown in FIG. 4 withthe terminals attached to its ends.

FIG. 6 is a sectional elevation of theterminalshown at the left end ofFIG. 5.

FIG. 7 is a perspective view of a modification of the cable shown inFIG. 1. 7

FIG. 8 is a perspective view of another modification.

The non-metallic conductor 10 provided for the ignition cable shown inFIG. 1 consists of individual threadlike filaments l2 impregnated withconductive material such as graphite. The individual filaments of theconductor 10 may be made of cotton, rayon, linen, dacron (polyester), orglass, or mixtures of the various filaments as desired. Referring toFIG. 1, the individual threads are preferably unreeled from storagespools and are immersed continuously as unreeled in a colloidal solutionof graphite in alcohol so as to completely impregnate the individualfibers of the threads. Upon issuing from the graphite solution, thethreads are gathered together in a suitable mechanical means and carriedinto a suitable drying oven as a group so that they are dried togetherin contact with each other which deposits the graphite as discreteparticles on the threads. The resistance of the final conductor is inpart determined by the number of threads which are joined together inthe gathering device so that, if a lower resistance is desired in thefinal cable as used in an ignition circuit, a larger number of thegraphite impregnated thread-like filaments are joined together. Thesubsequent conductor components in combination with the plurality ofconductive threads determine total resistance of conductor.

After the group of filaments have been dried in the drying oven, all ofthe threads as a group are passed through a suitable applicator whichapplies and impregnates all of the threads with a conducting rubberdissolved in a solvent so as to completely impregnate the whole group ofthreads. The impregnated coated strands are then conducted from theapplicator through a second drying and curing oven which removes thesolvents and also vulcanizes or cures the conducting rubber 14 by athermal action. The amount of conducting rubber must be considered whenit is desired to obtain a predetermined resistive value in the finalignition cable. The vulcanizable elastomeric material such as conductingrubber may be formulated with various concentrations of conductingmaterial to produce the predetermined resistive value desired in thefinal ignition cable.

The rubber coated non-metallic conductor is then passed through abraiding device which applies to the exterior of the conductor an openoverbraid 16 somewhat similar to a net which holds the individualthreads or filaments together to prevent aunitary conductor. Theoverbraid may be of any desired material such as cotton, rayon, linen,dacron (polyester), and glass, and is supplied to the conductor for thepurpose of increasing its strength or resistance to elongation whichmust also be considered in the selection of the material of which thebraid is made. The braid may also be made in a manner to completelyenclose the rubber coated conductor element if such is deemed necessary.

After leaving the braider which applies the overbraid 16 to theconductor, the conductor is passed into a suitable applicator whichapplies a second coating of conducting rubber 18. The conducting rubberis dissolved in a solvent and impregnates and coats both the braid andthe underlying conductor. It is then passed through a curing oven toremove the solvent and, to cure and vulcanize the conducting rubber.This completes the fabrication of the non-metallic conductor as anelement of the ignition cable.

The non-metallic conductor as fabricated by the steps describedhereinbefore is then provided with a coating 20 consisting of colloidalsolution of graphite in alcohol after which it is passed through an ovenfor the purpose of removing the solvent from the coating. This appliesto the exterior of the conducting rubber coated conductor an additionallayer 20 of conducting material in the form of graphite which also hasthe further function of allowing a conventional insulating material 22which is applied thereafter to be readily removed from the non-metallicconductor for the purpose of making suitable electrical connection witha terminal as will be described hereinafter.

The non-metallic conductor coated with the layer of graphite releasingagent 20 is then passed through a tuber which applies an extrusion orcoating 24 of insulating material to the exterior thereof whichpreferably consists of butadiene styrene rubber (SBR type), although anyof the normal insulating materials having suitable characteristics maybe used. The coated nonmetallic conductor is then placed in a vulcanizeror passed through a continuous vulcanizer which utilizes steam at asuitable pressure and temperature for curing or vulcanizing theinsulating coating which has been applied. The method and means forapplying this coating is well known in the art, and will not bedescribed in further detail.

For the purpose of increasing the strength in the final ignition cable,a second overbraid 26 is applied to the exterior of the insulatingcoating 24. Preferably, this braid is made from threads or filaments ofglass fiber in order to obtain maximum strength, although othermaterials may be used, such as cotton, rayon, linen, or dacron. The netor overbraid 26 is applied preferably as an open layer so that portionsof the underlying insulating coating 24 are exposed and capable of beingcontacted by a second outer insulating jacket or coating 28, preferablyof neoprene material which is also applied by passing the conductor withthe various jackets and overbraid through a tuber and vulcanizing thelast applied jacket in the same manner as described hereinbefore withthe first insulating coating 24. The neoprene material is preferablyused as an outer coating due to its inherent characteristics, such asoil resistance and the like. However, other commonly used jacketingmaterials such as chlorosulfanated polyethylene, butyl, BunaN and othersare suitable. With these steps, the fabrication of the ignition cable iscompleted, the whole operation being preferably carried out as acontinuous one in a mass production line.

The completed cable which is fabricated and reeled in long lengths, iscut to desired lengths, as shown in FIG. 2, preparatory to applyingmetallic terminals to the ends thereof as shown in FIG. 5. Theinsulation jackets or coverings 22, consisting of the two outer layers24 and 28 with the inner-positioned fiber glass net 26, as is best seenin FIG. 1, is cut away to bare the end portions of the non-metallicconductor as shown in FIG. 3. This can be accomplished in any convenientmanner using various cutting devices well known in the art. The outertwo jackets 22 with the inbedded glass overbraid may be readily removedfrom the nonmetallic conductor, due to the releasing layer 20 ofgraphite which has been applied to the exterior of the conductor asdescribed hereinbefore. The length of the non-metallic conductor whichis bared by removing the insulation 22 depends upon the type of terminalwhich is to be applied to the ends of the ignition cable.

The bared terminal portions A and B of the nonmetallic conductor arethen bent back over the insulating portion 22 of 'the ignition cable, asshown in FIG. 4 and while being held in this position, the terminals 30and 32 are applied to the ignitioncable by placing the clinching portionof the terminals 30a and 32a in embracing relation with the bent-overportions A and B of the nonmetallic conductor and the exterior of theinsulation of the cable. The terminals are positioned in a manner that asmall portion 22a of the cable insulation extends beyond the edge of theterminals. The clinching sections of the terminals are then crimpedtightly in position to embrace both the bent-over portions A and B ofthe non-metallic conductor and the exterior of the cable. The crimpingmay be brought about in various ways but, preferably, the crimpingpressure is concentrated on spaced, non-aligning areas 34 and 36 fromthe opposite sides of the cable as is best seen in FIG. 6. This causesthe terminal to place a heavy compression on all of the elements of thecable including the bentover portions A and B of the non-metallicconductor and also the overbraids l6 and 26 which are positioned on thenon-metallic conductor itself and between the insulating jackets 24 and28. This enhances the strength of the cable and its resistance toelongation when abnormal stresses are applied to the cable, inasmuch asall of the elements of the cable are anchored solidly together by theclinched terminals by placing the compression upon the cable adjacentits end. The cable then has the combined strength of the centralnon-metallic conductor with its overbraid, and that of the imbeddedoverbraid 26 which is positioned between the two insulating coatings.

In FIG. 7, a modification of the cable is shown in which the fiberstrands a are fabricated from fiberglass, cotton, rayon, linen orpolyester or mixtures thereof, and impregnated with conductive materialsuch as graphite. They are then positioned in parallel relation andcovered with an open overbraid 16a of cotton, rayon, linen, polyester orglass or mixtures of these various filaments as desired. The overbraid16a is then coated with conducting rubber in a solvent solution to forma conducting layer 180 which is applied in a manner similar to the stepdescribed with reference to the coating 18 of FIG. 1. The conductingcoating 18a flows through the overbraid 16a and superficially coats thefiberglass strands 10a of the central core member which is dried andvulcanized as described hereinbefore. After the conducting rubbercoating 18a has been vulcanized, the conducting releasing agent in theform of coating 20 is applied as before, and thereafter, the insulatingcoating 24, the imbedded overbraid 26, and the outer neoprene coating 28are applied as before described with reference to the modification shownin FIG. 1. This method of fabricating resistance cable is particularlysuited for a cable in which the core member is fabricated fromfiberglass strands.

In the modification shown in FIG. 8, the central core member 10, withits various layers, is the same as the cable described and shown in FIG.1, the only difference being that the imbedded reinforcing overbraid 26,which is positioned between the insulating layers 24 and 28, has beenomitted.

The attachment of the terminal pieces 30 and 32 to the ends of thecables shown in FIGS. 7 and 8 is identical to that described withreference to the modification shown in FIG. 1. The insulation is cutaway to expose the central conductor as shown in FIG. 2, the insulationbeing removed at the conducting releasing layer 20 in the mannerdescribed hereinbefore. Thereafter, the exposed terminating portions Aand B are bent back over the outer insulation and the metallic terminalpieces 30 and 32 are applied by crimping as has already been described.

It is to be understood that the above detailed description of thepresent invention is intended to disclose an embodiment thereof to thoseskilled in the art, but that the invention is not to be construed aslimited in its application to the details of construction andarrangement of parts illustrated in the accompanying drawings since theinvention is capable of being practiced and carried out in various wayswithout departing from the spirit of the invention. The language used inthe specification relating to the operation and function of the elementsof the invention is employed for purposes of description and not oflimitation, and it is not intended to limit the scope of the followingclaims beyond the re quirements of the prior art.

We claim: 1. In combination, an ignition cable having an outer sheath ofelectrical insulation material and an inner core of nonmetallic fibrousstrands coated with an electrically conductive carbonaceous material;said core having an end portion thereof extending beyond one end of saidsheath and folded over said one end of said sheath; said end portion ofsaid core being impregnated with a conductive medium comprising adispersion of carbon particles in a resinous base for binding thestrands of said end portion of said core together, and an electricalterminal having a ferrule portion of sheet metal extending around andtightly crimped onto said end of said sheath and the impregnated endportion of said core with said ferrule portion in electricallyconductive engagement with said impregnated core. 2. In combination, anignition cable having an outer sheath of electrical insulation materialand an inner core of nonmetallic fibrous strands coated with anelectrically conductive carbonaceous material; said core having an endportion thereof extending beyond one end of said sheath and folded oversaid one end of said sheath;

said end portion of said core being impregnated with a conductive mediumcomprising a dispersion of carbon particles in an elastomeric materialfor binding the strands of said end portion of said core together, and

an electrical terminal having a ferrule portion of sheet metal extendingaround and tightly crimped onto said end of said sheath and theimpregnated end portion of said core with said ferrule portion inelectrically conductive engagement with said impregnated core.

1. In combination, an ignition cable having an outer sheath ofelectrical insulation material and an inner core of non-metallic fibrousstrands coated with an electrically conductive carbonaceous material;said core having an end portion thereof extending beyond one end of saidsheath and folded over said one end of said sheath; said end portion ofsaid core being impregnated with a conductive medium comprising adispersion of carbon particles in a resinous base for binding thestrands of said end portion of said core together, and an electricalterminal having a ferrule portion of sheet metal extending around andtightly crimped onto said end of said sheath and the impregnated endportion of said core with said ferrule portion in electricallyconductive engagement with said impregnated core.
 2. In combination, anignition cable having an outer sheath of electrical insulation materialand an inner core of non-metallic fibrous strands coated with anelectrically conductive carbonaceous material; said core having an endportion thereof extending beyond one end of said sheath and folded oversaid one end of said sheath; said end portion of said core beingimpregnated with a conductive medium comprising a dispersion of carbonparticles in an elastomeric material for binding the strands of said endportion of said core together, and an electrical terminal having aferrule portion of sheet metal extending around and tightly crimped ontosaid end of said sheath and the impregnated end portion of said corewith said ferrule portion in electrically conductive engagement withsaid impregnated core.